In recent years, there have been high expectations for the realization of large-screen, wall-hung televisions as two-way information terminals. In the field of display panels, research is being performed into a variety of devices, such as liquid crystal displays, field emission displays, and electroluminescent displays. Some of these have already been placed on the market, while others are under development.
Of these display devices, plasma display panels (PDPs) are self-luminous type, and enables large-screen televisions with high-quality image display to be realized. Thus, PDPs offer distinctive features which cannot be found in other types of display devices.
Typically, PDPs have a construction in which discharge cells of different colors are arranged in the form of matrix. In the case of surface discharge ac (alternating current) PDPs, a front glass substrate and a back glass substrate are set in parallel with each other with barrier ribs being interposed in between. Display electrode pairs (pairs of scan electrodes and sustain electrodes) are formed in parallel with each other on the front glass substrate. A dielectric glass layer is formed on the front glass substrate so as to cover the display electrode pairs. Meanwhile, address electrodes are formed on the back glass substrate so as to cross over the scan electrodes at right angles. Red, green, and blue phosphor layers are provided in the spaces partitioned by the barrier ribs between the front and back glass substrates. A discharge gas is enclosed in these spaces. Hence a panel construction where discharge cells of different colors are formed is obtained.
To drive such a PDP, a voltage is applied to each electrode using a drive circuit. This causes discharge to occur in the discharge cells, which emit ultraviolet light. The ultraviolet light excites phosphor particles (red, green, and blue) in the phosphor layers to emit light. Hence an image is displayed.
To achieve high image quality in the PDP, it is necessary to adjust the amount of light emitted in each colored cell so that a high color temperature can be obtained when white is being displayed. Generally, the light intensity of a blue phosphor is weaker than the other two colors. Accordingly, in conventional PDPs adjustments are made using drive circuits to make the discharge in the blue cells larger than the discharge in the other colored cells. In so doing, the amount of light emission for each color is balanced.
Also, it is important for PDPs to display images at high luminance with low power consumption.
To achieve high luminance, it may be effective to increase discharge intensity by reducing the film thickness of the dielectric layer. However, just making the dielectric layer thinner does not have an effect of improving the illumination efficiency of the phosphor layers, but rather tends to cause a drop in illumination efficiency.